The Law on Self-Defense
In sum, a person can defend herself using force against someone else, only to the extent that this force is necessary for protection. Physical force is never permissible in law if it is used while the person defending herself is carrying out a crime. The self defense law will not enable a person to use force as a reaction to someone verbally abusing (you bolded this, but here you falsely equate "verbally abusing" to "the perception of an imminent threat of death from a credible source") them. Self defense law does not enable a person to have provoked the fight in the first place.
Let’s take the example of Jeff and Bob.
Example 1: Jeff is walking down the road. Bob is walking towards Jeff. Bob takes out a knife and points it at Jeff while he runs at him aggressively. Jeff did not provoke Bob to do this, but he thinks Bob is going to stab him, or cut him. Jeff is permitted to take out a knife in his own defense because he is not the aggressor. It is also possible, depending the specific facts, that Jeff could take out a gun as well since, Bob has displayed a deadly weapon (the knife).
Example 2: Bob is running toward Jeff. Jeff does not know Bob. Jeff takes out a gun, and shoots Bob, killng him. This scenario would not enable Jeff to successfully use self defense during his murder trial. It was not reasonable for Jeff to believe he needed to shoot Bob. The measure of force was not reasonable. It is not clear given this example whether any force was necessary at all. A person can only use force against another when there is a clear imminent threat of bodily harm or death (you bolded this, but obviously chose to actually ignore it since it explicitly points out that you are wrong. Also, the scenario doesn't apply to the situation at hand, so I suppose this is just your yet another attempt to "cherry-pick" various sentences or phrases to try to prove that which is unable to be proven?).
Example 3: On July 28th, 2012, Jeff tells Bob he is going to kill Bob. Bob sees Jeff with a loaded gun on the same day. Jeff enters the premises, and Bob thinks Jeff still has the loaded gun. Bob can shoot Jeff and raise Self Defense during his case.
Example 4: Bob is driving Jeff home. Jeff threatens to kill Bob and tells him that he has a gun under the car floorboard. Jeff then begins grabbing at Bob. Bob pulls car over and shoots Jeff. Self defense can be raised in this situation.
Example 5: Medical examiner testifies that Bob was stabbed 52 times all over his body. Jeff raises self defense at his trial. Self defense law will not protect Jeff in this circumstance because 52 stabbings are not “reasonably necessary” to protect oneself. The only force permitted is the minimum amount of force necessary to prevent the imminent bodily harm or death (you chose to ignore this, but "minimum amount of force necessary..." obviously indicates that the amount of force able to be used is not definitive beyond the minimum applicable based on the situation).
It should be noted that Baker’s Texas Penal Code Handbook from 2008 clearly indicates that more often than not (in other words, not always)in Texas, a defendant fails to succeed in using the self defense law to get out of the criminal charges. Self defense it extremely fact dependent. All of the surrounding circumstances will be assessed by the jury when they are deciding whether the use of force was permissible under the self defense law (pretty self explanatory). For instance, killing someone and then afterwards acting casually about it, can lead to a jury finding that you were not a victim employing self defense, but rather an aggressor trying to hide behind the self defense law. How a person acts (notice the omission of attributing the word "acts" to "the person acting in self-defense" -- because it applies to both parties) before, during and after the assaultive event will be looked at with a microscope by an able jury.